Thermal electric cut-out.



R. H. MAPLE.

THERMAL ELECTRIC CUT-OUT.

APPLICATION FILED NOV. 20. i914.

Patented Apr. 2, 1918.

A TTORNEY W lT/VESSES: a//

BOY x. mm, or mmeneroms, mourn.

THERMAL ELECTRIC CUT-OUT.

Specification of Letters Patent.

RElSSUED Patented Apr. 2, 1918.

Application filed November 20, 1914. Serial No. 878,216.

To all whom z'tma concern:

Be it known t at I, ROY H. MAPLE, a

citizen of the United States, and a/ resident of Indianapolis, county of Marion, and

State of Indiana, have invented a certain new and useful Thermal Electric Out-()ut; and I do hereby declare that the followin is a full, clear, and exactdescription thereo reference bein had to the accompanying drawings, in w ich like letters refer to likeparts.

The object of this invention is to provide a thermo-electric circuit breaker or out out which has a very few number of parts and is designed primarily for use on low voltage circuits, such as those used with battery illumination. This form of circuit breaker has a high momentary overload capacity for short periods of time and in low voltage lam circuits the extremely low resistance of t e filaments causes a heavy flow of current until they become sufficiently heated to cause a circuit breaker, not having the characteristics mentioned, to be set beyond this peak. current load. The setting of a circuit breaker for this momenta overload would render it useless for sma overloads such as caused by-grounds and partial short circuits. The type described in this application will operate successfully if any load above the normalis continued for any length of time.

Another feature of the invention consists in formin such a device so that it will perform the a ve function and withoutchanging circuits as an ordinary switch. In this last mode of operation of the device, the

thermostat does not operate. In other words the device operates as an ordinary switch when the thermostat is carrying the regular load. The free end of the thermostat coiiperates with the movable switch member in making the circuit and another resetting movable member moves the free end of the thermostat out of engagement with the free end of the switch member for breaking the circuit. so this forms an ordinary make and break switch and yet the circuit will be automatically broken on the occasion of temperature change influencin the thermostat. The device, therefore, 1s a combined thermostatic switch and manually operated switch.

The full nature of the invention will be understood from .the accompanying drawings and the following description and claims. 1

In the drawings, Figure 1 is a side elevation of the swltch with the parts in circuit closing position and with parts in section. Fi 2 is an elevation of the righthand an of Fig. 1 and showing two switches'and-both' switches closed and with parts in section. Fig. 3 is a plan view of the device shown in' Fig. 2 with the top plate removed. Fig. 4 1s a plan view of Fig. 2 including the top plate. Fig. 5 is a section like Fig. 1 of a modified form. Fig. 6 is a perspective view of the end of the thermal spring.

In the drawings herein shown there is a base plate 10 formed of hard rubber and having in it a binding post 11 which also screws upon the plate 10. There is a spring switch member 12 consisting of a plate formed of spring metal and with the, two sides thereof bent upward so as to press against each other normally and with the upper ends spread away from each other somewhat to permit the entrance between them of the movable member 13 of the switch. This makes substantially a hife switch and may be made in any suitable form, as the invention is not limited to any particular construction of the switch members. The movable switch member 13 has secured to it a hard rubber push button 14 that reciprocates through a late 15.. It also has an inwardly exten ing arm 17 which is angular in cross section and extends through a correspondingly shaped hole in the base plate 10 and reciprocates therein. A spring 18 is located around the arm 17 and lies'between the plate 10 and the switch member 13 and its function is to return or force outward said switch member after it has been forced inward and released. The switch member 13 has a nose piece 20 on it with a curved edge or surface, as shown in Fig. 1, adapted when the switch member 13 is pushed inward to pass below the free end 21 of a thermal strip 22. When the switch member 13 is in such inward position, it will be held there in spite of the action of the spring 18, by said end 21 of the thermostat until said roe end of the thermostat is moved so as to release the switch member 13 and then thespring 18 returns it and breaks the circuit.

The thermal strip 22 is coiled about a horizontal arm 25 extending from a vertical stand 26. The horizontal arm is slotted to receive the inner end of the thermal strip and then said strip is coiled about the same and the free end of .the strip is bent back on itself to enlarge said end and provide a curved surface and also provide engagement members for trip member 35 on the end thereof for engaging the curved sur faces of the nose 20 of the switch member 13. The end of the thermal strip is located so as to engage the nose of the switch member 13 and as the switch member 13 is pushed inward the end 21 of the thermal To insure the circuit passing e from the thermal strip to the switch memsprin shoulder 31 an the plate 10.

strip'pames the point of the nose 20 and en ages the surface on the upper or outer si e of said nose and holds the switch member 13 inward in circuit making osition. ectively ber 13 a pig tail 27 is provided connecting them substantially as shown in Fig. 1, and arranged so as not to interfere with the movements of the two members of said arts. p The plates 10 and 15 are held spaced apart by suitable posts or screws 127. The parts of the mechanism so far described operate as a thermostatic switch. In normal position the circuit is broken. When, however, the switch member 13 is pushed inward, the parts assume the position shown in Fig. 1 and the circuit is closed by'the knife edge of the member 13 entering between the contacts 12 and the thermal strip will old the parts 12 and 13 in electrical connection until the thermal strip 22 is heated eausin it to expand and to some extent unwin thus moving the end 21 of said thermal strip away from the nose 20 of the switch member 13. Then the switch member 13 returns to normal position under the action of the spring 18 and out of enement with the spring contacts 12.

l To enable said thermostatic device to be used also as an ordinary manually operated switch there is a lateral projection 30 from the free end of the thermal strip in position to be enga ed by a shoulder 31 and push rod 32 mounte tension 33 on said push rod 32 reciprocates in the base plate 10 and the push rod is re turned by a s ring 34 lying between the Assuming that the circuit has been operated so as to close the circuit by depressin the button 14 on the switch member 13, an

' it is desired to break the circuit manually,

in the plates 10 and 15. An ex that the free end of the thermal strip ma more effectually engage and hold the switc member in circuit closing position, the swltchmember is provided with a notch 40 above 1ts end and with a substantially regular curvature into which the bent free end of the thermal strip lies. The effect of this is that the notch provides a shoulder against which the free end of the thermal strip bears so that when the strip is heated, said engagmg end will move away from the switch member at a substantially right angle to the portion thereof which it had been engaging.

Locklng means is also provided consisting of the laterally movable bolt 41 mounted in the casing adapted to be operated by any suitable key 42 so that when the bolt is actuated, it will engage a notch 43 in the end of the switch member and prevent its operat1on or movement.

The arm 26 is held in lace and from turning by being made angu ar so as to have a lower plate that sets down in the recess 42 in the base 10 and is secured thereto by a screw 43, as seen in Fig. 3.

The invention claimed is:

1. A thermal switch having a coiled thermal stri in the circuit thereof, a/movable switch c osing member in position to be held closed by the free end of said thermal strip,

a spring for returning said switch member after its release, and means for positively disengaging the free end of the thermal strip in the circuit thereof, a lateral projection near the free end of said strip, a movable switch member for closin the circuit and in position to be held 010 by the free end of said thermal strip, a push rod for engaging the lateral projection from the thermal strip and moving it so as to release the switch member, and means for returnin the switch member and push rod to norma position.

4. switch including a coiled thermal strip in the circuit thereof, a lateral roj ect1on near the free end of said therma strip, a movable switch member for closing the circult and in position to be held closed by the free end of said thermal strip, a push rod for engaging the lateral projection from the thermal strip and moving it so as to release stantially at a right'angle to t the switch member, and springs for returning the switch member and push rod to normal position.

5.- A thermal switch having an arm, a thermal stri secured at one end to said arm and coiled about the same with the free end of said strip bent back on itself, and a movable switch member having an inwardly turned end provided with a curved notch into which said curved free end of the thermal strip is adapted to enter and hold the switch member closed, the parts being arranged so that the releasing movement of the free end of the thermal stri will be sube portion of the switch engaged thereby.

6. A thermal switch havin two parallel separated plates in fixed re ation to each other, a thermal strip mounted between said plates and with one end thereof secured in xed position and the other end thereof free, a contact located between said plates, a

switch member slidably and non-rotatably mounted in said plates in position to be moved into and out of engagement with the free end of said thermal strip and with said contact, and a spring ,for returning switch member after it has been moved into such engagement. f

7. A thermal switch having two parallel separated plates in fixed relation with each other, a coiled thermal strip mounted between said lates and with one end thereof secured in xed position and the other end thereof free, a contact between said plates and in fixed relation therewithand with said thermal stri a push rod extending through said plates and arranged so as to be nonrotatable, a, switch member secured on said push rod so as to be movable thereby into position to engage both the free end'of said thermal strip and said contact, and a sprin on said push rod for returning the same and the switch to normal outward position.

In witness whereof, I have hereunto afed my signature in the presence'of the witnesses herein named.

J. H. Wm, B. Looxwoon. 

